Relay.



B. H. SMITH.

RELAY. APPLICATION FILED DEC-29, 1914- RENEWED SEPT-16.1916. 1,273,940. Patented July 30, 1918.

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WITNESSES INVENTOR I Be jaHQn/f vjmiffi.

UNITED STATES PATENT OFFICE.

BENJAMIN H. SMITH, TURTLE CREEK, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AN MANUFACTURING COMPANY, A. CORPORATION OF PENN SYL- VANIA.

RELAY.

Specification of Letters Patent. Patented July 30, 1918,

Application filed December 29, 1914, Serial No. 879,496. Renewed September 16, 1916. Serial No. 120,583.

To all whom it may concern:

Be it known that I, BENJAMIN H. SMITH, a citizen of the United States, and a resident of Turtle Creek, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Relays, of which the following is a specification.

My invention relates to relays, and it has for its object to provide a relay having means for compensating for the torque thereof, under predetermined conditions of adaptable for inverse time-limit operation.

Since a substantially definite time-limit relay is often desirable for selective and numerous other operations, I provide means for so compensating a relay, of the above mentioned type, that it Will develop a torque that is either substantially proportional to the current traversing the circuit to be protected or substantially constant, according to the effect desired.

In the accompanying drawings, Figure 1 is a diagrammatic front elevational view of a relay constructed in accordance with my invention, and Fig. 2 is a diagram of load time curve that may be obtained by a relay embodying my invention, and Fig. 3 is a side elevational view of the relay shown in Fig. 1.

A relay 1 is provided with a magnetizable core 2 having an upwardly projecting central member 3,'side members 4 separated from the central member by small air gaps 5 and joined to the central member 3 by yoke members 6, and downwardly projecting members 7 that are separated from the central member 3 and the side members 4, at their lower ends by air gaps 8, and connected to the side members 4, at their other ends, by yoke members 9. A disk armature.

10 is mounted upon 'a shaft 11 and is disposed in the air gaps 8, substantially as shown in Fig. 1 of the drawings. A main winding 12 is disposed upon the central member 3, and a primary auxiliary winding 13 is disposed on one of the yoke members 6 and electrically connected to secondary auxiliary windings 14 that are disposed on the downwardly projecting members 7.

The members 7 are so proportioned that they become magnetically saturated when a predetermined current traverses the winding 12, depending, of course, upon the shape of the load-time curve desired. The members 7 may be so proportioned that they are saturated at all values of current in their windings 14, in which instance, the loadtime curve obtained will more nearly approach a definite time limit in its characteristics. Any of the well known methods of arranging the members 7, so that they become easily saturated, may be employed. It will, of course, be understood that, when the members 7 are not saturated, the torque, of the relay will be substantially proportional to the square of the current traversing the winding 12.

he armature 10 is adapted to move between the poles of a permanent magnet 15 for 'the purpose of retarding the same a definite amount, and a spiral spring 16, having one of its ends attached to the shaft 11 and its other end to a stationary member 17, is also provided to assist the damping magnet 15 in retarding the operation of the armature 10 to'obtain various speeds, and therefore, diiferent. time characteristics, if the torque of the relay remains substantially constant.

When current traverses the winding 12 the magnetic lines of force therefrom induce a voltage in the winding 13 Which causes current to traverse the windings 1.4. If the members 7 are not magnetically saturated, the armature will develop a torque that is substantially proportional to the square of the current traversing the :winding 12. However, by reason of the relatively small cross section of the members 7, a very small value of current in the windings 14 causes the members 7 to become magnetically saturated and, no matter how much more current traverses the winding 12, only a predetermined number of magnetic lines of force will be carried by the members 7. Thus, the armature 10 will tend todevelop a torque that is substantially proportional to the first power of current traversing the winding 12. However, the torque will not be proportional to the current because of the shifting of the phase diflerence between for all values of current after thp-members 7 become saturated.

It will be noted that thewinding 13 is preferably placed on one of the yoke members v6 for the purpose or increasing'the leakage of the magnetic lines of force from the winding 12 tostill further reducing the current that traverses the winding let when the current in the winding 12 increases.

As hereinbefore stated, the members 7 may be adapted to become saturated under any predetermined condition and thus the load-time curve obtained will follpw a substantially inverse time-limit law until the members 7 become saturated, then the curve will become substantially parallel to the base line, Thus, it will be seen that the curve shown in Fig. 2 may be caused to assume its straight line direction under various conditions. The heights of the various curves obtained however, are dependent upon the retardation provided by the damping magnet 15 and the spring 16, any of the well known methods being employed to vary the tension on the spring or the travel of the armature.

While I have shown my invention in a preferred form, 1t is not so "limited, but is capable of various modifications within the scope of the appended claims.

I claim as my invention:

1. A relay comprising a magnetizable core having a central member, two side members joined to one end of the central member and separated therefrom at its other end by small air gaps and downwardly projecting members separated from the (ventral member and the side members at one end by small air gaps and joined thereto at their other end, a winding disposed on the central member and windings on the downwardly projecting members inductively connected to the winding on the central memher, said windings disposed on the downwardly projecting members being so, proportioned and the downwardly projecting members having such cross-sectional area thatthey are magnetically saturated'at pre determined values of current traversing their windings.

2. A relay comprising a movable armatune, a magnetizable core member, a main winding upon the core member, and an auxiliary winding upon the core member that is inductively related to the main winding, the portion of the core member surrounded by the auxiliary winding becoming saturated under usual conditions of use of the relay at a predetermined value of current traversing the winding, whereby a substantially uni-form force is caused to be exerted upon the armature for all currents in excess of the said predetermined value.

3. A relay comprising a movable armature, a magnetizable core member, a main winding upon the core member, and an auxiliary winding upon the core member that is inductively related to the main winding', the portion of the core member surrounded by the auxiliary winding becoming saturated under usual conditions of use or the relay at a predetrmined value of current traversing "the winding, whereby the force exerted upon the armature varies with the current traversing the said windings up to the said predetermined value, and a substantially uniform force is caused to be ex erted upon the armature for all currents in excess of said predetermined value,

4:. A relay comprising a magnetizable core member provided with a plurality of polar projections having opposing faces that are separated by a narrow air gap, a rotatable armature occupying the said air gap, a main winding surrounding one of the said pro= jeotions, and an auxiliary winding inductively'related to the main winding and sur rounding other projections which become saturated at a predetermined value of current traversing the auxiliary winding, the flux produced by the auxiliary winding being thereby retarded in phase-angular relation with respect to the flux produced by the main winding and a substantially uniform force being exerted upon the armature the said presaturated at a predetermined value or our l the auxiliary winding, the.

rent traversin flux produced y the auxiliary winding being thereby retarded in phase-angular relatlonv with respect to the flux produced by the main winding, andtheforce exerted upon the armature being thereby caused to vary with the amount ofcurrent traversin the windings up the said predetermined value and to remain substantially unitonn when the current exceeds the predeteed value,

Mill

. winding upon the core member, and an auxiliary Winding that is inductive'l related to the m-ain winding and surroun a por tion of the core mem'ber that becomes saturated when the currenttraversing the winding under usual operating conditions of the relay exceeds a, predetermined Value, Whereby the flux produced by the auxiliary winding is retarded in phase-angular relation with respect to the flux produced by the main winding and a. substantially uniform force is caused to be exerted upon the armature when the current exceeds the said 15 predetermined value.

In testimony whereof, I have hereunte subscribed my name this 22nd day of Dec.,

v BENJAMIN H. SMITH.

Witnesses: I

. GEO. M. LITTLE,

B. B. HINES. 

